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Additional Guidance for Misfire Fault Codes

Technical Service Bulletin
Technical Service Bulletin: TSB230065
Additional Guidance for Misfire Fault Codes

Released Date: 11-Jul-2024

Additional Guidance for Misfire Fault Codes
Warranty Statement
The information in this document has no effect on present warranty coverage or repair practices,
nor does it authorize TRP or Campaign actions.

Contents
Product Affected
L9 CM2450 L126B
Issue Summary
Symptom:
Misfire fault codes without any audible misfire or performance loss (false misfire):
Table 1, Misfire Fault Codes
Fault Code

Fault Description

5895

Engine Misfire Cylinder #1 - Root Cause Not
Known

5896

Engine Misfire Cylinder #2 - Root Cause Not
Known

5897

Engine Misfire Cylinder #3 - Root Cause Not
Known

5898

Engine Misfire Cylinder #4 - Root Cause Not
Known

5899

Engine Misfire Cylinder #5 - Root Cause Not
Known

5911

Engine Misfire Cylinder #6 - Root Cause Not
Known

5914

Engine Misfire for Multiple Cylinders - Root
Cause Not Known

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Additional Guidance for Misfire Fault Codes

Root Cause:
The misfire diagnostic can be overly sensitive in certain conditions in some applications and
can generate incorrect faults code. Running in PTO mode is particularly sensitive to these
fault codes.
Verification
Verify that one or more of the listed fault codes are active or inactive with more than one
count within the last 25 engine operating hours.
If all misfire fault codes are active, follow troubleshooting for Fault Code 2374.
Verify there are no performance complaints with the unit.
Run the injector performance test on the injectors. See corresponding Service Manual.
Reference Procedure 014-014 in Section 14.
Service Instructions
Follow the steps below to confirm the engine speed when Misfire Fault Code 5899 was set:
1. Check Engine Speed at Time of Misfire Fault Code
Connect the recommended Cummins® electronic service tool or equivalent to the ECM.
Select Fault Codes. See Figure 1.

Figure 1, Fault Codes.
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Additional Guidance for Misfire Fault Codes

Locate misfire fault code and select expand icon. See Figure 2.

Figure 2, Expand Fault Code Information.
Locate Engine Speed by scrolling down. See Figure 3.

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Additional Guidance for Misfire Fault Codes

Figure 3, Scroll Down for Engine Speed.
Add Engine Speed and confirm Engine Speed at time Misfire fault code logged. See Figure 4.

Figure 4, Confirm Engine Speed.
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Additional Guidance for Misfire Fault Codes

Resolution
Do not replace injectors unless injector performance test results say to replace injector(s)
Recommended to change the PTO speed to less than 2000 rpm if feasible. Changing the PTO
speed can clear the false fault condition.
Run the vehicle in PTO mode to verify if the fault returns.
If 5899 misfire fault code is logged and first or last engine speed value is in the engine speed
range of 2000 rpm to 2175 rpm, compare the ECM code and revision number in the ECM to
the calibration revision listed in the ECM Calibration Revision History Database on
QuickServe® Online (QSOL) for applicable changes. If an ECM calibration code update for this
fault code is available, the ECM calibration code revision must be that revision or higher.
Operate the engine within the “Conditions for Clearing the Fault Code” found in the Overview
section of the troubleshooting procedure.

Document History
Date

Details

2023-3-23

Module Created

2024-6-24

Updated Verification and Resolution.

Last Modified: 11-Jul-2024

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